Implantable electrical stimulator

ABSTRACT

An implantable stimulator is provided for stimulating muscles or nerves. The implantable stimulator may comprise an array of electrodes for electrically stimulating at least one of a nerve or a muscle of a subject, and at least one processing device. The at least one processing device may be configured to detect, based on signals received from the array of electrodes, a measurement of an electromyography signal; dynamically select one or more electrodes within the array of electrodes to stimulate the nerve or muscle, the one or more electrodes being selected based on the measurement in order to stimulate a desired area of the nerve or muscle; and receive, from an external device, power used both to activate the selected electrodes and to stimulate the nerve or muscle

FIELD OF THE INVENTION

The present invention relates generally to an implantable electricalstimulator and more specifically to an implantable electrical stimulatorwith a dynamically controlled electrode array.

BACKGROUND OF THE INVENTION

Implanting a stimulator to stimulate muscles or nerves is a complexprocedure. Generally in the case of nerve stimulation, a specialelectrode is used, such as a cuff electrode. Generally the electrode isin the form of a wire extending from the stimulator to the nerve.Implantation of the stimulator requires surgical intervention to exposethe position for implanting the electrode and stimulator and thenrequires fine-tuning the placement of the electrode so that accuratecontact will be formed between the electrodes of the stimulator andspecific contact points along the muscles or nerves.

In the case of muscle stimulators, the electrodes are typicallypositioned to form contact with the motor end plate of a muscle, alsocalled the neuromuscular junction of the muscle. In most muscles themotor end plate is located in the middle of the muscle, where the motorneuron interfaces with the muscle.

In recent years manufactures have managed to reduce the size ofstimulators significantly, for example to approximately 3 mm by 27 mm.In a reduced size stimulator the electrode may be provided as a rigidmetal contact extending from the body of the stimulator and thestimulator is implanted with the electrode positioned in contact withthe muscle/nerve contact points.

One method to achieve the correct positioning is by trial and error,wherein the practitioner inserts the stimulator to a selected positionand then provides a charge to the electrodes of the stimulator to verifythe position according to the response of the muscles, for examplecontraction of the entire muscle indicates a successful positioning andlocal contraction indicates an unsuccessful positioning. This methodrequires a high level of expertise from the practitioner and may be verytime consuming.

Another method suggests the use of a probe that also serves as theintroduction device for the stimulator. The practitioner uses the probeto locate the desired position and then uses the probe to insert thestimulator to the located position.

Some problems may occur after positioning the stimulator. One problem isthat a rigid stimulator may damage the muscles/nerves or surroundingtissue and lead to complications, for example causing inflammation,which may reduce tissue conductivity, so that the stimulator device maynot stimulate the muscles/nerves properly. A second problem that mayoccur is movement of the stimulator and/or electrodes, which may cause ashift in the electrode alignment. The shift in the electrode alignmentmay reduce stimulation of the muscles/nerves thus preventing thestimulator from effectively causing tissue stimulation.

U.S. Pat. No. 7,447,551 to Kuo et al. the disclosure of which isincorporated herein by reference describes using a flexible circuitboard in creating an implantable stimulator. The stimulator is coatedwith a flexible bio-compatible package material to enhance safety,durability and reliability of the implantable stimulator. Kuo furtherdiscloses using an array of electrodes to enlarge the electricaltreatment area and improving the electrical treatment efficiency.

SUMMARY OF THE INVENTION

An aspect of an embodiment of the invention, relates to an implantablestimulator for stimulating muscles and/or nerves, with a dynamicallycontrollable array of electrodes. The array of electrodes is made upfrom one or more rows and one or more columns of electrodes positionedon a surface that can be placed in contact with a muscle/nerve.Optionally, the stimulator may have multiple arrays, for example one oneach side of the stimulator or even multiple arrays on each side of thestimulator. In an exemplary embodiment of the invention, the array ofelectrodes has a density greater than the density of the muscle/nervecontact points, which need to be stimulated; or the array of electrodesoccupies an area larger than that of the muscle/nerve contact point. Inany of the above two options, once the stimulator is initiallypositioned at least some of the electrodes will coincide with theposition of the contact points.

In an exemplary embodiment of the invention, the stimulatorautomatically determines which electrodes are in contact with points onthe muscle/nerve wherein the action potentials signals measured at thosepoints indicates that they are desirable contact points. The propertiesmeasured for an action potential signal may include among other details:frequency, amplitude, and propagation speed. Optionally, when relatingto muscle stimulation, the contact points are generally located in themotor units, which include the neuromuscular junction.

In an exemplary embodiment of the invention, the method of selecting aspecific electrode or group of electrodes may include measuring theaction potentials amplitudes, and creating time integrals, for exampleby using Root Mean Square to determine the location of the muscle'sMotor Units. Alternatively or additionally, other algorithms, such asdecomposition algorithms, or Correlation Kernel Compensation, may helpto determine the location of the muscle's Motor Units. Optionally, theelectrodes that are close or in contact with the muscles Motor Units areselected as having measured the lowest resistance at the electrodecontact point and those electrodes are used to stimulate themuscles/nerves of the patient. Optionally, the determination may be madeperiodically or upon request of the patient or practitioner. In analternative embodiment of the invention, the practitioner that installsthe stimulator, communicates with the stimulator wirelessly using acomputer and selects the electrodes that elicit the most prominentclinical reaction.

In an exemplary embodiment of the invention, the array of electrodes isused to identify contracting regions. The controller in the stimulatorcan then choose to stimulate the contracting regions or thenon-contracting regions.

In some embodiments of the invention, the electrodes serve as inputs andoutputs. Alternatively, some of the electrodes serve as inputs and someserve as outputs. Optionally, the inputs measure the resistance orelectrical activity of the muscle/nerve at their contact point with themuscle/nerve.

In some embodiment of the invention, the stimulator is made up from afew basic rigid elements, for example an integrated circuit to controlthe stimulator, a memory chip, a power source (e.g. a battery), atransceiver and other elements. Optionally, each element is wrappedseparately in a bio-compatible encasement and connected with flexiblewiring or a common flexible backbone serving as a communication busbetween the elements of the stimulator, thus providing a flexiblestimulator, In an exemplary embodiment of the invention, the electrodesare provided as a separate element made up from an array of contacts ona flexible material, for example, wherein the material is made up fromPolyimide, Polyester or PEEK thermoplastic with the electrodes embeddedin it.

There is thus provided according to an exemplary embodiment of theinvention, an implantable stimulator for stimulating muscles or nerves,including:

an array of electrodes for electrically stimulating muscles or nerves;

a controller for controlling the activity of the electrodes;

wherein the controller is adapted to dynamically select the electrodesthat are used to participate in stimulating the muscles or nerves.

Optionally, the implantable stimulator further includes a power sourceto power the stimulator.

In an exemplary embodiment of the invention, the implantable stimulatorfurther includes a transceiver to wirelessly communicate with externaldevices and receive commands for the controller.

Optionally, the controller selects the electrodes responsive to acommunication from an external device.

In an exemplary embodiment of the invention, the controller periodicallyupdates the selection of electrodes to participate in stimulation of themuscle or nerve.

Optionally, the controller selects the electrodes responsive to adetermination made by electrical measurements made by the electrodes.

In an exemplary embodiment of the invention, substantially all theelectrodes can serve as inputs to measure electrical activity in themuscles or nerves and as outputs to electrically stimulate the musclesor nerves.

Optionally, some of the electrodes serve as inputs to measure electricalactivity in the muscles or nerves and some of the electrodes serve asoutputs to electrically stimulate the muscles or nerves.

In an exemplary embodiment of the invention, the density of the array ofelectrodes is greater than the density of the active contact points ofthe muscle or nerve being stimulated by the stimulator.

Optionally, the array of electrodes is connected by flexible wires tothe other elements of the stimulator.

In an exemplary embodiment of the invention, the stimulator is made upfrom multiple independent parts connected together electrically by aflexible connection.

Optionally, the stimulator is made up from flexible material. In anexemplary embodiment of the invention, the array of electrodes forms athree-dimensional shape shielding the controller in saidthree-dimensional shape.

In an exemplary embodiment of the invention, the implantable stimulatorfurther includes a housing, and said controller is located within thehousing.

Optionally, the implantable stimulator further includes a housing, andthe controller, and the power source are located within the housing.

In an exemplary embodiment of the invention, the stimulator is adaptedto be implanted at the base of a person's tongue.

Optionally, the implantable stimulator further includes sensors to sensephysiological parameters of the person with the implanted stimulator.

In an exemplary embodiment of the invention, the sensors are adapted tosense physical parameters from the group consisting of temperature,vibrations, and audio signals.

Optionally, the stimulator is activated responsive to measurementsreceived by the sensors.

In an exemplary embodiment of the invention, the power source receivespower wirelessly.

There is further provided according to an exemplary embodiment of theinvention, a method of stimulating muscles or nerves using animplantable stimulator with an array of electrodes, including:

dynamically selecting the electrodes that will participate instimulating the muscle or nerve from the available electrodes; and

activating the selected electrodes to stimulate a muscle or nerve.

In an exemplary embodiment of the invention, the method further includesimplanting the stimulator so that the array of electrodes is inproximity with a muscle or nerve.

Optionally, the selection is performed manually by a practitioner bycommunicating with the stimulator and instructing the stimulator toactivate one or more electrodes or groups of electrodes while observingthe response.

Alternatively or additionally, the selection is performed by theelectrode array measuring electrical parameters through one or moreelectrodes or group of electrodes and making a selection based on theresults of said measurements.

Optionally, the selection is performed by the electrode array measuringelectrical parameters through an external device.

In an exemplary embodiment of the invention, the selection is repeatedperiodically.

Optionally, the selection is activated responsive to inputs accepted bythe stimulator.

In an exemplary embodiment of the invention, the selection is activatedresponsive to sensor input.

Optionally, dynamically selecting further includes performing apre-programmed algorithm to weigh the results from various inputs anddetermining whether to provide stimulation.

In an exemplary embodiment of the invention, the method further includesdetermining the specific stimulation protocol to provide.

Optionally, the dynamic selection is responsive to electricalmeasurements at the location of the electrodes.

In an exemplary embodiment of the invention, the dynamic selection isresponsive to responsiveness of the nerve or muscle at the location ofthe electrodes.

Optionally, the method further includes adjusting the stimulatorresponsive to a measurement before activating the stimulator.

In an exemplary embodiment of the invention, the stimulation is providedat specific times, for specific time duration, or periodically.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be understood and better appreciated from thefollowing detailed description taken in conjunction with the drawings.Identical structures, elements or parts, which appear in more than onefigure, are generally labeled with the same or similar number in all thefigures in which they appear, wherein:

FIG. 1 is a schematic illustration of a block diagram of an electricalstimulator, according to an exemplary embodiment of the invention;

FIG. 2A is a schematic illustration of an electrical stimulator withindependent elements connected by flexible wires, according to anexemplary embodiment of the invention;

FIG. 2B is a schematic illustration of an electrical stimulator withindependent elements connected by a flexible backbone serving as acommunication bus, according to an exemplary embodiment of theinvention;

FIG. 3A is a schematic illustration of a flexible electrode array shapedas a tent, according to an exemplary embodiment of the invention;

FIG. 3B is a schematic illustration of a flexible electrode arrayshielding beneath it other elements connected together by a flexiblewire, according to an exemplary embodiment of the invention;

FIG. 3C is a schematic illustration of a flexible electrode arrayshielding beneath it other elements connected together by a flexiblecommunication bus, according to an exemplary embodiment of theinvention;

FIG. 3D is a schematic illustration of a flexible electrode arrayimplanted at the base of the tongue, according to an exemplaryembodiment of the invention;

FIG. 4A is a schematic illustration of a flexible electrode array shapedas a flat surface, according to an exemplary embodiment of theinvention;

FIG. 4B is a schematic illustration of a flexible electrode array shapedas a cylinder, according to an exemplary embodiment of the invention;

FIG. 4C is a schematic illustration of a flexible electrode array shapedas a 3 dimensional curved surface with electrodes on the inner side,according to an exemplary embodiment of the invention;

FIG. 4D is a schematic illustration of a flexible electrode array withbranches of electrodes extending from a common center, according to anexemplary embodiment of the invention;

FIG. 4E is a schematic illustration of a flexible electrode array withbranches of electrodes of various sizes extending from a common center,according to an exemplary embodiment of the invention; and

FIG. 5 is a flow diagram of a method of using a stimulator, according toan exemplary embodiment of the invention.

DETAILED DESCRIPTION

FIG. 1 is a schematic illustration of a block diagram of an electricalstimulator 100, according to an exemplary embodiment of the invention.In an exemplary embodiment of the invention, stimulator 100 includes anelectrode array 110, which is designed to be placed in contact with thecontact points of nerves or muscles, or in proximity thereof, so thatthe electrodes can stimulate the contact points. Optionally, theelectrode array is denser than the contact points on the muscle or nerve(e.g. 1-100,000 electrodes per millimeter, or per centimeter) or thearray of electrodes occupies an area larger than that of themuscle/nerve contact point, so that each contact point on the muscle ornerve that needs to be stimulated will have one or more electrodes 115in contact with it. In some embodiments of the present invention, someor all of the electrodes can be placed in proximity with the contactpoints of nerves or muscles. In the context of the present inventionplaced, includes, but is not limited to implanted, inserted, injected,wrapped, and in any other way positioned in contact or in proximity tocontact points of nerves or muscles. In some embodiments of theinvention, the tips of the electrodes that are in contact with thepatients tissue may be any shape, for example circular or rectangular.Optionally, the tip may be flat or rounded to prevent electrode array110 from getting stuck if placed in contact with the patient's tissuebefore reaching its final position. Alternatively, the tips of theelectrode may be coated with materials that encourage tissue fibrosis.Alternatively, the tips may be thorn like to anchor stimulator 100. Inan exemplary embodiment of the invention, electrodes 115 are made of orplated with a bio-compatible metal (e.g. a noble metal like platinum orgold).

Optionally, the shape of electrode array 110 is selected based on thetype of nerve or muscle needed to be stimulated. In some embodiments ofthe invention, the shape may be one dimensional (e.g. a line ofelectrodes), two dimensional or three dimensional.

In an exemplary embodiment of the invention, an electrode arraycontroller 120 is used to control the electrodes 115 of electrode array110. Optionally, electrode array controller 120 can be used to select ordeselect any of the electrodes 115, so that when stimulator 100 outputsa stimulation pulse the selected electrodes will output the pulse. Insome embodiments of the invention, some electrodes are output electrodesand some are input electrodes. Alternatively, the electrodes can beselected to be either input or output. Optionally, electrode arraycontroller 120 can use input electrodes as input sensors, for example toserve as an electromyograph (EMG), detecting the resistance/conductivityor action potential of the muscles/nerves in contact with a specificelectrode. Optionally, such a measurement can be used to locate thedesired area for stimulation of the muscle or nerve and determine whichelectrodes 115 are in contact with the desired areas.

In an exemplary embodiment of the invention, due to external forcesexerted on stimulator 100 after being embedded in a patient, the exactposition of the electrode array may shift and electrodes 115 that werepreviously selected to stimulate contact points may shift over and otherelectrodes may be in contact with the muscle/nerve contact points intheir place. As explained above the electrodes participating instimulating the muscles/nerves of the patient are dynamicallyselectable, so that the electrodes 115 participating in stimulating themuscles/nerves can be reselected to overcome such problems.

In an exemplary embodiment of the invention, stimulator 100 includes acontrol circuit 130, which includes a general purpose CPU or anapplication specific integrated circuit (ASIC) or the like to controlthe functionality of the stimulator, for example to determine when toprovide a stimulation signal and the parameters of the signal, forexample its frequency, pulse width, pulse shape, pulse interval andpulse duration. Optionally, control circuit 130 is preprogrammed toapply various stimulation programs, such as:

1. A nerve stimulation program;

2. A muscle stimulation program; and

3. Biphasic stimulation that alternates polarization on the electrodes115 to prevent accumulation of ions and acidosis thus reducing tissuedamage.

Optionally, each program may use different pulse frequency, shapes,widths, intervals, durations and other parameters for the stimulationsignal applied to the electrodes.

In some embodiments of the invention, stimulator 100 includes a memory140, for example a non-volatile memory that is used to store operationalparameters or program code which the control circuit can act upon,

Optionally, stimulator 100 further includes a power supply 160, whichmay include a rechargeable battery, for example a Li-Ion battery.Alternatively or additionally, the power supply may include a capacitorand/or coil for holding charge for a short term until charging thebattery or for immediate consumption. In an exemplary embodiment of theinvention, the power for using the device is provided by wirelesstransmission of power to a power receptor 170, for example an inductioncoil or RFID coil. In an exemplary embodiment of the invention,stimulator 100 may be activated as long as power receptor 170 isaccepting transmitted power. Alternatively, stimulator 100 is firstcharged and then activated to consume the power from power supply 160.Further alternatively, priority is giving to the stimulation: firststimulating by passing the received power transmission directly to thestimulation circuit, and then charging.

In some embodiments of the invention, stimulator 100 includes atransceiver 150 for communicating between stimulator 100 and an externaldevice, such as a personal computer 180 or an external activation device190 that is designed to communicate with stimulator 100.

In some embodiments of the invention, the communications and/or powertransfer are performed using a non-standard protocol to preventinterference from standard communication equipment. Alternatively,standard communication protocols may be used, for example communicatingwith WIFI, BlueTooth (BT), RF or other common standards so thatstimulator 100 can readily communicate with standard equipment that isreadily available, such as personal computer 180 or a cellular telephone(e.g. using BT). Optionally, communications with stimulator 100 may beencrypted and/or require authentication to prevent undesirabletransmissions from non-authorized users. Alternatively or additionally,a predefined range of transmission frequencies is used so it will notinterfere or receive interference from other radio emitting devices.

In some embodiments of the invention, stimulator 100 includes one ormore sensors 125 that sense various parameters such as temperature,sound, vibrations, pressure, electrical current, impedance, and thelike. Alternatively or additionally, stimulator 100 receives wirelesscommunication from sensors implanted elsewhere in the patient or locatedoutside of the patient. Optionally, muscle/nerve stimulation can beactivated responsive to the measurements of sensors 125. In someembodiments of the invention, stimulator 100 may activate stimulationresponsive to specific combinations of measurements. An example of useof an internal or external sensor occurs in dealing with ObstructiveSleep Apnea (OSA). During sleep a person inhales colder air (e.g. atroom temperature of about 25° C.) and exhales warmer air (e.g. at bodytemperature of about 37° C.). Optionally, stimulator 100 may be plantedat the base of the tongue adjacent to the air path of the patient'sbreath. A temperature sensor can follow the breathing pattern byfollowing the temperature changes and alert stimulator 100 to stimulatethe tongue muscles responsive to a determination that the tongue isblocking the path. Alternatively, an external sensor can be positionedover the patient's mouth or nose to keep track of the breathing pattern.

In some embodiments of the invention, sensor 125 is used to measure theelectrical current or impedance of specific electrodes to determine theimportance of the specific electrode in stimulating the nerve/muscle atthe current position of stimulator 100 and electrode array 110.

FIG. 2A is a schematic illustration of an electrical stimulator 200 withindependent elements 220 connected by flexible wires, according to anexemplary embodiment of the invention; and FIG. 2B is a schematicillustration of an electrical stimulator 250 with independent elements270 connected by a flexible backbone 280 serving as a communication bus,according to an exemplary embodiment of the invention. In an exemplaryembodiment of the invention, as illustrated above in FIG. 1 stimulator100 is made up from various elements. Optionally, each element maycomprise a rigid electronic circuit or other rigid parts (e.g. abattery, a coil, a capacitor, an integrated circuit), which communicateelectronically with the other elements of stimulator 100. In someembodiments of the invention, as illustrated in FIG. 2A by stimulator200, elements 220 are electronically connected by flexible wires 210,thus providing a larger overall flexible stimulator 200. Alternatively,as illustrated in FIG. 2B, elements 270 are connected to a flexiblecommunication bus 280, forming an overall flexible stimulator 280.Optionally, a flexible stimulator is less apt to be damaged by externalforces and can be more easily manipulated to fit into various positionsinside the patients body. Additionally, a flexible stimulator such asshown in FIGS. 2A or 2B will also allow free 3D movement of an organ(e.g. muscle) without causing damage. Optionally, the flexibleconnection between the elements enables the elements to be freelypositioned relative to each other and effectively allow bending orfolding of stimulator 100.

In an exemplary embodiment of the invention, electrode array 110 isdesigned to match the muscle or nerve it will be interfacing. FIG. 3A isa schematic illustration of a flexible electrode array 300 shaped as atriangular tent, according to an exemplary embodiment of the invention.In an exemplary embodiment of the invention, the flexible electrodearray is shaped to fit the nerve or muscle it is to be placed inside ornext to. In another exemplary embodiment of the invention, the flexibleelectrode array is shaped to fit a recess between nerves or tissue, acompartment in muscles or between tissues, or an epimysial surface. Suchrecess, compartment or surface can naturally occur or be artificiallycreated. Electrode array 300 is densely populated (e.g. between 1×1 to1000×1000 electrodes 310 per millimeter square or more, or less) and itis designed to be used to stimulate the Genioglossus muscle at the baseof the tongue for treatment of Obstructive Sleep Apnea (OSA). It shouldbe noted that the above design is not limiting and other designs canalso be used for treatment of OSA.

FIG. 3B is a schematic illustration of a flexible electrode array 300shielding beneath it other elements 330 connected together by a flexiblewire 320 and FIG. 3C is a schematic illustration of a flexible electrodearray 300 shielding beneath it other elements 330 connected together bya flexible communication bus 325, according to an exemplary embodimentof the invention; In other exemplary embodiments of the invention, theflexible electrode array can comprise a shape forming a housing, or beplaced on a housing, said other elements 330 connected together areplaced within said housing.

In an exemplary embodiment of the invention, electrode array 300 isconnected by flexible wires 320, as shown in FIG. 3B, to elements 330and battery 340, which constitute the elements of stimulator 100.Alternatively, electrode array 300 is connected by flexible bus 325, asshown in FIG. 3C, to elements 330 and battery 340, which constitute theelements of stimulator 100. In some embodiments of the invention,battery 340 is not part of the elements of simulator 100. Alternativepower sources to battery 340 can include a capacitor, super capacitor,piezo-electric charging material, mechanical (induced by body or otherorgan or tissue movement) or chemical (such as ionic difference) powersources, coil or a coil having a ferrite core, and the like. In oneexemplary embodiment of the invention action potential generated byneurons and nerve tissue across the nerve or muscle are gather via theelectrode array and stored in a capacitor (not shown). The actionpotential translated into energy can be used to power the device of theinvention. In an exemplary embodiment of the invention the housing ismade of flexible bio compatible material such that the entire device isflexible.

The triangular tent shape of array 300 and the other shapes disclosedherein, assists in forming contact between electrodes 310 and thecontact points at the base of the Genioglossus muscle, or morespecifically near the compartments of the Genioglossus oblique fibers,and above the Geniohyoid muscle. Additionally, the triangular tent shapeprovide for a cavity or an opening underneath thereof that can beexploited to store other elements 330 and battery 340 or other powersources of stimulator 100 by folding them up or placing them beneatharray 300 or within said housing (not shown).

FIG. 3D is a schematic illustration of flexible electrode array 300implanted at the base of the tongue, according to an exemplaryembodiment of the invention. Optionally, electrode array 300 is designedso that when it is deployed, electrodes 310 will be in contact with theGenioglossus muscle 350 and more specifically adjacent to theGenioglossus horizontal fibers 350 and/or near the Hypoglossal nerves360, so that electrodes 310 will successfully be able to stimulate theGenioglossus horizontal compartment causing dilation of the pharynxduring breathing. Optionally, the shape of electrode array 300 isespecially efficient in stimulating the Genioglossus muscle 350, as thismuscle has numerous motor end plates, located in various locations incontrast to many other muscles.

FIGS. 4A-4E provide various exemplary shapes, of electrode arrays to beused to position the electrode array in proximity with the muscles ornerves that are to be stimulated by the electrodes of the array. Theexemplary shapes include:

1. A flat surface 400;

2. A cylinder 410;

3. A 3 dimensional curved surface 420 with electrodes on the inner sideto match a cylindrical muscle/nerve;

4. A flexible electrode pad 430 with branches of electrodes extendingfrom a common center; and

5. A flexible electrode pad 440 with branches of electrodes of varioussizes extending from a common center.

Optionally, other shapes may be used to maximize contact between theelectrodes and the muscles/nerves. In an exemplary embodiment of theinvention, the shape is designed to match the muscles/nerves thatstimulator 100 is designed to stimulate.

FIG. 5 is a flow diagram 500 of a method of stimulating muscles ornerves using implantable stimulator 100 with an array of electrodes,according to an exemplary embodiment of the invention. In an exemplaryembodiment of the invention, a medical practitioner implants (510) thedevice. The implantation process depends on the location and type ofmuscle/nerve to be stimulated. Optionally, due to the small size ofstimulator 100 (e.g. with a length and width between 0.01 mm to 10 mm) anon-invasive procedure is preferable, for example by injecting thedevice using a hypodermic needle with local anesthesia only. Optionally,the use of a point and shoot insertion method is preferable, since it ismore comfortable for the patient and less invasive. Optionally accordingto the present invention, stimulator 100 is advantageous since themultiplicity of electrodes relative to the number of contact points onthe muscle/nerve and the ability to select the optimal electrodes forstimulation after implantation, reduce the need to adjust the positionof stimulator 100 responsive to actual stimulation during the insertionprocess. An example of use of a stimulator 100 is in dealing withObstructive Sleep Apnea patients. In an exemplary embodiment of theinvention, stimulator 100 is implanted in the vicinity of theHypoglossal nerve using a shallow transcutaneous approach. In othercases stimulator 100 is implanted into the Genioglossus muscle using anintraoral or transcutaneous/submandibular approach.

Optionally, after implanting stimulator 100 the practitioner may adjust(520) the implanted stimulator responsive to an Ultrasound, MRI, CT,X-ray or other measurements before activating the stimulator 100. Insome embodiments of the invention, the implantation is performed using apoint and shoot process that does not require additional adjustments,however in some cases, usually depending on the type of stimulator andposition of implantation in the patient's body further measurements maybe required to verify accurate positioning, and further adjustments maybe needed. In some embodiments of the invention, the implantationprocedure is performed while using an imaging device (such asUltrasound, MRI, CT, or X-ray) to guide the practitioner in locating theexact implantation site.

Once stimulator 100 is positioned the electrode array controller 120dynamically selects (530) the electrodes from electrode array 110 thatwill be used to stimulate the muscle/nerve.

In some embodiments of the invention, the selection is performedmanually by the practitioner, for example by communicating withstimulator 100 (e.g. with computer 180) and either instructingstimulator 100 to activate single electrodes or groups of electrodeswhile observing the response, and/or instructing stimulator 100 to usethe electrode array 110 to measure electrical parameters such asresistance, conductance, or EMG signals, for each electrode or forgroups of electrodes. Optionally, the practitioner may also measure aresponse via an external device, for example a surface EMG, fiber optic,manometer, polysomnograph, pulse oximeter, EEG, microphone.

In some embodiments of the invention, the selection may be performedautomatically by electrode array controller 120, wherein electrode arraycontroller 120 measures EMG signals, or other signals, and dynamicallyselects (530) the electrodes that will participate in the stimulationprocess responsive to the measurements.

In some embodiments of the invention, stimulator 100 automatically,repeats the dynamic selection process before every use, or periodically(e.g. every day or every week or before the next use, or atpredetermined intervals) to verify that stimulator 100 has not moved andto remedy the situation if it has. Such predetermined intervals can bedetermined through a preprogrammed plan or reprogrammed when sorequired, or ad hoc as per each use. For example, the dynamic selectioncan be performed every few seconds or every few minutes or on an hourlybasis and the like.

In some embodiments of the invention, stimulator 100 is activated (550)responsive to various inputs accepted (540) by stimulator 100.Optionally, the inputs may be based on physiological parameters of thepatient or may be based on commands from an external source such asexternal activation device 190. In an exemplary embodiment of theinvention, external activation device 190 is used to activate thestimulator whenever the patient feels the need, for example whensuffering pain or when interested that muscles controlled by stimulator100 be activated.

Optionally, when treating OSA, the patient may activate stimulator 100when going to sleep, and stimulator 100 will perform muscle/nervestimulation responsive to sensors that determine that the patient'stongue needs to be stimulated to enable the patient to breathe.Optionally, external activation device 190 may be a simple transmitterwith one or more buttons or switches 195 to transmit signals tostimulator 100 and to select from a few options, for example tostimulate immediately, periodically or responsive to sensormeasurements. Alternatively a general purpose computer 180 can be usedto program stimulator 100 by transmitting simple or complex commands andreceiving responses from stimulator 100. In some embodiments of theinvention, external activation device 190 supplies power to stimulator100. Optionally, stimulator 100 may be activated (550) whenever power isprovided. Alternatively, it may charge power supply 160 and be activated(550) at a later time.

In some embodiments of the invention, stimulator 100 may sense variousphysiological parameters of the patient with sensors 125, for example:

1. Specific periodic vibrations or lack of vibrations from the patient'srespiratory system;

2. Temperature in the vicinity of stimulator 100, for example a highertemperature value responsive to the patient expiration in the vicinityof the implanted stimulator 100 and a lower temperature value responsiveto the patient inspiration in the vicinity of stimulator 100. A decreasein the temperature change may indicate reduction in breathing;

3. Audio signals, for example, keeping track of the patient's heartbeat,breathing/snoring pattern, or breathing/snoring sounds. Optionally, adecrease in the volume of breathing sounds may indicate an OSA event;

4. EMG signals, for example, keeping track of the patient's muscle tone.Optionally, a decrease in the patient's muscle tone may indicate an OSAevent. Optionally, an increase in the patient's respiratory auxiliarymuscle tone may indicate an OSA event.

In some embodiments of the invention, sensors are placed at otherpositions on the patient's body and they communicate wirelessly withstimulator 100.

In some embodiments of the invention, control 130 may perform apre-programmed algorithm to weigh the results from various inputs anddetermine if to stimulate or not. Optionally, control 130 can beprogrammed to decide the specific stimulation protocol (e.g. pulsewidth, pulse amplitude, pulse shape).

In some embodiments of the invention, stimulator 100 operatesindependently, without receiving any feedback. Optionally, stimulator100 is pre-programmed to stimulate at specific times, for specific timeduration, or to stimulate periodically, for example for 10 seconds everyhour.

It should be appreciated that the above described methods and apparatusmay be varied in many ways, including omitting or adding steps, changingthe order of steps and the type of devices used. It should beappreciated that different features may be combined in different ways.In particular, not all the features shown above in a particularembodiment are necessary in every embodiment of the invention. Furthercombinations of the above features are also considered to be within thescope of some embodiments of the invention.

It will be appreciated by persons skilled in the art that the presentinvention is not limited to what has been particularly shown anddescribed hereinabove. Rather the scope of the present invention isdefined only by the claims, which follow.

1-34. (canceled)
 35. An implantable stimulator for stimulating musclesor nerves the implantable stimulator comprising: an array of electrodesfor electrically stimulating at east one of a nerve or a muscle of asubject; at least one processing device configured to: detect, based onsignals received from the array of electrodes, a measurement of anelectromyography signal; dynamically select one or more electrodeswithin the array of electrodes to stimulate the nerve or muscle, the oneor more electrodes being selected based on the measurement in order tostimulate a desired area of the nerve or muscle; and receive, from anexternal device, power used both to activate the selected electrodes andto stimulate the nerve or muscle.
 36. The implantable stimulator ofclaim 35, wherein the power for activating the selected electrodes isused for causing a muscle contraction.
 37. The implantable stimulator ofclaim 36, wherein the implantable stimulator is located in a vicinity ofthe subject's tongue; and the power for activating the selectedelectrodes is used to cause a contraction of a genioglossus muscle ofthe subject.
 38. The implantable stimulator of claim 37, wherein thepower for activating the selected electrodes is used to further causedilation of a pharynx.
 39. The implantable stimulator of claim 35,wherein the at least one processing device is further configured toreceive stimulation signals from the external device.
 40. Theimplantable stimulator of claim 35, wherein the power received from theexternal device through wireless transmission.
 41. The implantablestimulator of claim 35, wherein at least one processing device isfurther configured to receive a command from the external device and totransmit responses to the external device.
 42. The implantablestimulator of claim 35, wherein the measurement s indicative of asleep-apnea related event
 43. The implantable stimulator of claim 35,wherein the measurement is indicative of a precursor to a sleep-apnearelated event.
 44. The implantable stimulator of claim 35, wherein theselected electrodes are activated whenever power is provided.
 45. methodfor stimulating muscles or nerves, the method comprising: detecting, byan implantable stimulator and based on signals received from an array ofelectrodes for electrically stimulating at least one of a nerve or amuscle of a subject, a measurement of an electromyography signal;dynamically selecting one or more electrodes within the array ofelectrodes to stimulate the nerve or muscle, the one or more electrodesbeing selected based on the measurement in order to stimulate a desiredarea of the nerve or muscle; and receiving, from an external device,power used both to activate the selected electrodes and to stimulate thenerve or muscle.
 46. The method of claim 45, wherein the method furthercomprises causing a muscle contraction using the received power.
 47. Themethod of claim 46, wherein the implantable stimulator is located in avicinity of the subject's tongue and the method further comprisescausing a contraction of a genioglossus muscle of the subject using thereceived power.
 48. The method of claim 47, wherein the method furthercomprises causing a dilation of a pharynx using the received power. 49.The method of claim 45, wherein the method further comprises receivingstimulation signals from the external device.
 50. The method of claim45, wherein the external device is a transmitter configured towirelessly transmit power to the implantable stimulator.
 51. The methodof claim 45, wherein the method further comprises receiving a commandfrom the external device and transmitting responses to the externaldevice.
 52. The method of claim 45, w herein the measurement isindicative of a sleep-apnea related event.
 53. The method of claim 45,wherein the measurement is indicative of a precursor to a sleep-apnearelated event.
 54. The method of claim 45, wherein the method furthercomprises activating the selected electrodes whenever the power isprovided.